Rub resistance is a highly desired property for lithographic inks. Such resistance is needed not only during the end use properties of the printed product, but also during prior processing stages (such as laminating, cutting, and creasing). Because lithographic inks have a high pigment-to-resin ratio, the binder resin usually does not provide all the necessary surface protection needed to prevent rub damage.
The traditional method of addressing this problem of rub damage has been to add a wax to the ink formulation. However, the addition of wax has adverse effects on the characteristics of the ink (among which are a decrease in the gloss of the ink and an increase in the time required to dry the ink).
Therefore, an object of this invention is to solve this major problem by disclosing an improved method of producing resin compositions that exhibit properties which makes them useful in formulating vehicles for lithographic printing inks and other coating applications.
A further object of this invention is to produce lithographic printing inks with enhanced rub resistance.